Crimp height adjustment mechanism

Abstract: A crimp height adjustment mechanism (4) is disclosed for use in a crimping machine having an anvil (42) and a ram (44) carrying a crimping die (46). The ram is secured against rotation and guided for reciprocal movement along a ram axis (R-R) for moving the crimping die toward and away from the anvil. A drive member (52) is connected for reciprocating the ram. The adjustment mechanism includes a first member (10) fixed with respect to the anvil and having a first threaded portion (12) of a first thread pitch extending along an adjustment axis parallel to the ram axis. A second member (20) has a second threaded portion (22) coaxial to the first threaded portion. The second threaded portion has a second thread pitch which differs from the first thread pitch. The second member is secured against rotation and coupled to move the ram linearly along the ram axis. A third member (30) has both a third threaded portion (32) which is threadedly engaged with the first threaded portion, and a fourth threaded portion (34) which is threadedly engaged with the second threaded portion. The third member is rotatable about an adjustment axis (A-A) so as to change an extent of engagement with the first and second threaded portions. Rotation of the third member about the adjustment axis produces a linear movement of the second member which is equal to a number of rotations of the third member multiplied by a difference between the first and second pitches.

Description: The invention generally relates to a machine for crimping a terminal to an electrical conductor, and more particularly, to a mechanism which enables extremely fine adjustment of the height of a crimped terminal produced in such a machine. Machines are known for crimping a terminal to an electrical conductor such as a wire or cable. Such machines generally employ a ram which is reciprocally movable with respect to a fixed anvil. The ram carries a crimping die which cooperates with the anvil to crimp a terminal therebetween. In a crimping operation, the ram is driven through a working stroke to deform the terminal and tightly engage the conductor within the terminal to form a crimped connection. The crimp height, i.e., the height or vertical dimension of the terminal after deformation, is a good indicator of quality of the crimped connection. In order to produce a secure and reliable crimped connection, the terminal must be deformed around the conductor until the height of the terminal is below a certain maximum. Terminals and conductors come in a variety of types and sizes, and the maximum is predetermined for many different combinations of terminals and conductors. Based on pullout tests which measure the tension required to separate crimped terminals of various crimp heights from their associated conductors, the maximum crimp height for a particular combination of terminal and conductor can be calculated. Ideal crimp heights are somewhat below the maximum so as to provide a safety factor against pullout while avoiding excessive deformation of the terminal which may in itself destroy the crimped connection and requires greater energy to produce. A crimping machine which has been set up to produce a certain crimp height may require adjustment after some time in operation. The need for adjustment may be due to wear of components in the machine, non-uniformity of terminals being crimped, or a change in the type or size of the terminal or conductor. Various mechanisms for adjusting crimp height are known. These mechanisms provide either a means to vary the working stroke of the ram or a means to adjust a rest position of the ram with respect to the anvil, thereby adjusting a dimension from the crimping die to the anvil when the ram is at the fullest extent of its working stroke. The known adjustment mechanisms are somewhat coarse, generally being unable to achieve crimp height adjustments in increments smaller than 0.00254 cm (.001 inch). There is a need for a mechanism that provides extremely fine crimp height adjustments and that is easy to set to a desired value. US-A-4,707,913 discloses a terminal applicator for crimping a terminal onto the end of a wire, the apparatus including an anvil and a movable die mounted on a shuttle ram. The die is coupled to an actuator via an adjustable link having a variable length. WO-A-88/09576 discloses a pressing apparatus in which a tooling ram is coupled to press ram via a threaded member, which is rotatable by means of a bushing. Rotating the bushing causes the threaded member to be moved linearly. W. Krause "Konstruktionselemente der Feinmechanik", 1989, VEB Verlag Technik, Berlin, pages 710, 711 and 717 to 719 discloses an adjustment mechanism comprising a first fixed member having a first threaded portion with a first pitch, a second member being secured against rotation and having a second threaded portion with a second pitch, and a third rotatable member having both a third and a fourth threaded portion engaged with said first and second threaded portions, respectively. Rotation of the third member produces a linear movement of the second member which is equal to the number of rotations of the third member, multiplied by a difference between the first and second pitches. The invention provides a crimp height adjustment mechanism as defined in claim 1. Preferred embodiments thereof are defined in the dependent claims. The invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a side view of a crimping machine having a crimp height adjustment mechanism according to the invention. Figure 2 is a cross-sectional view of the crimp height adjustment mechanism according to the invention, taken along line of Figure 1. Figure 3 is an isometric view of the crimp height adjustment mechanism. Figure 4 is an isometric view of the crimp height adjustment mechanism, as viewed from a different direction. Figure 5 is an exploded isometric view of the crimp height adjustment mechanism shown in Figure 3. Figure 6 is an exploded isometric view of the crimp height adjustment mechanism shown in Figure 4. Figure 7 is an isometric partial view of a manual adjustment wheel for the crimp height adjustment mechanism. With reference to Figure 1, a crimp height adjustment mechanism according to the invention is shown generally as 4 in use on a crimping machine having a frame 58 which supports an anvil 42 and a ram 44 carrying a crimping die 46 at one end. The ram is guided for reciprocal movement along a ram axis R-R for moving the crimping die toward and away from the anvil between remote and proximate positions with respect to the anvil. As shown in the drawings, the ram has a rectangular cross-section and is disposed in a ramway of guideframe 92 of the machine frame 58. The guideframe 92 ramway guides the ram during its reciprocal movement and also secures the ram against rotation about the axis R-R. Of course, other arrangements for securing and guiding the ram will be readily apparent to those skilled in the art, and the crimp height adjustment mechanism of the present invention is equally well-suited for use with others of those arrangements. The crimping machine further includes a drive member such as extensible cylinder 52 which is connected via bellcrank 66 and toggle link 68 for reciprocating the ram 44 and moving the crimping die 46 between the remote and proximate positions. The extensible cylinder 52 is operable via air or hydraulic forces received through connections (not shown) to extend or retract cylinder rod 54. One end of the cylinder 52 is connected by pivot pin 62 to the machine frame 58. The rod 54 is pivotally connected by clevis 72 with the bellcrank 66, which in turn has a pivotal connection 74 with the adjustment mechanism 4. The pivotal connection 74, which acts as a fulcrum for the bellcrank 66, is generally fixedly disposed during stroking of the cylinder 52, being linearly movable only during occasions of crimp height adjustment between strokes of the cylinder 52. The toggle link 68 has pivotal connections 76, 78 with the bellcrank 66 and the ram 44, respectively, thus completing a connection for reciprocating the ram 44 upon actuation of the cylinder 52. As with the guideframe 92 for securing and guiding the ram, other types of drive members and other arrangements for connecting a drive member to reciprocate the ram will be readily apparent to those skilled in the art and are considered to be within the scope of the invention. The crimping die 46 is adapted to cooperate with the anvil 42 to crimp a terminal (not shown) onto a conductor when the crimping die is in the proximate position. As shown in Figures 1-6, the crimp height adjustment mechanism 4 of the present invention is housed in a retainer 6 which is attached to the machine frame 58 by retainer key 86 extending through slot 38 in the retainer 6. Referring now to Figures 2, 5 and 6, a first member 10 comprises a hub that is fixed within the retainer 6. The hub 10 has longitudinal splines 16 around its outer periphery, and a setscrew 18 threaded in the retainer 6 engages between two of the splines 16 and prevents rotation of the hub within the retainer. The hub 10 has a central bore 14 extending along an adjustment axis A-A which is parallel to the ram axis R-R. A wall of the central bore 14 defines screw threads which provide a first threaded portion 12 having a first thread pitch which is preselected as will be more fully described hereinafter. In a preferred embodiment as shown in Figure 1, the adjustment axis A-A of the adjustment mechanism 4 is coincident with the ram axis R-R. Referring now to Figures 1, 2, 5 and 6, a second member 20 comprises a yoke shaft having a yoke 26 at one end which receives the pivotal connection 74 within holes 28 for joining with the bellcrank 66. The yoke shaft 20 is secured against rotation about the adjustment axis A-A by engagement of the yoke 26 in the guideframe 92 ramway. An other end of the yoke shaft 20 is threaded so as to define a second threaded portion 22 which is coaxial to the first threaded portion 12. The second threaded portion 22 has a second thread pitch which is selected to be different from the first thread pitch. The yoke shaft 20 is coupled to the ram 44 through the bellcrank 66 and the toggle link 68 such that linear movement of the second member 20 along the adjustment axis A-A produces a corresponding linear movement of the ram along the ram axis R-R. A third member 30 comprises an adjuster shaft having an external periphery and a coaxial bore. The external periphery defines a third threaded portion 32 which is threadedly engaged with the first threaded portion 12 of the hub 10. The wall of the coaxial bore defines a fourth threaded portion 34 which is threadedly engaged with the second threaded portion 22 of the yoke shaft 20. In each instance the threaded engagement is loosely adjustable, i.e., the adjuster shaft 30 is rotatable about the adjustment axis A-A within the hub 10 and on the yoke shaft 20. Rotation of the adjuster shaft 30 causes an increase or decrease in the extent of engagement with the first threaded portion 12 and the second threaded portion 22. In the preferred embodiment, each of the first, second, third and fourth threaded portions comprises right hand screw threads, i.e., clockwise rotation of the adjuster shaft produces forward movement thereof. From the viewpoint of an observer at the left hand side of Figure 2, clockwise rotation of the adjuster shaft 30 results in increasing engagement between the first threaded portion 12 and the third threaded portion 32. Thus, one rotation of the adjuster shaft 30 results in linear movement of the adjuster shaft to the right over a distance equal to the first thread pitch. Simultaneously, the fourth threaded portion 34 increasingly engages with the second threaded portion 22. However, since the second thread pitch has been selected to be different from the first thread pitch, one rotation of the adjuster shaft 30 results in linear movement of the yoke shaft 20 over a distance equal to the difference between the first and second pitches. When the first thread pitch 12 is greater than the second thread pitch 22, clockwise rotation of the adjuster shaft 30 results in right hand movement of the yoke shaft 20. Conversely, counter-clockwise rotation of the adjuster shaft 30 results in left hand movement of the yoke shaft 20. The first and second pitches are selected so that a difference between them is quite small. Actuation means enabling rotatable movement of the adjuster shaft 30 includes a manually gripable adjustment wheel 48. The wheel 48 has a groove 94 which allows passage for a drive pin 56 coupled to the adjuster shaft 30 which engages with a cap 88 or a motor coupler 96 and is secured with screw 98 for rotating the adjuster shaft. A stop collar 40 attached by threaded fasteners (not shown) to the retainer 6 limits axial movement of the adjustment wheel 48. Preferably, circumferential surface 82 of the adjustment wheel 48 has alignment marks 84 at regular intervals, as shown in Figure 7. By successively aligning the marks 84 with a fixed indicator on the adjustment apparatus 4, the adjuster shaft 30 can be rotated in precise steps in order to effect precise changes in crimp height. In an embodiment of the crimp height adjustment mechanism preferred by applicants, the first thread pitch is 14 threads per inch, i.e. 0.181 cm (.0714 inch) and the second thread pitch is 18 threads per inch, i.e. 0.141 cm (.0555 inch). The difference between the first and second pitches is approximatively 0.04 cm (.016 inch). The surface 82 of the adjustment wheel 48 has 32 of the marks 84 spaced at regular intervals 11.25 degrees apart around the circumference thereof. It is very easy to rotate the adjustment wheel 48 through an interval of 11.25 degrees to change alignment from one mark 84 to the next. Such a rotation of the adjustment wheel effects a change in crimp height of 0.0013 cm (.0005 inch), with more precision and repeatability than prior devices for changing crimp height. The actuation means may also include, either in addition to or in place of the adjustment wheel 48, an automatic means such as adjuster motor 64, shown in Figure 1, which is connected for rotating the adjuster shaft 30 in response to a signal from a sensor (not shown). For example, the adjuster motor 64 can be electrically connected to a crimp height monitor such as that disclosed in U.S. Patent No. 4,856,186 or U.S Patent No. 4,916,810. The motor 64 can be programmed to make automatic crimp height adjustments when the crimp height monitor detects crimps that are out of specification. Further, the adjuster motor can be programmed to make a sequence of adjustments in order to perform a sequence of crimping operations requiring different crimp heights. As shown in Figure 2, it is preferred that the first, second, third and fourth threaded portions 12, 22, 32 and 34, respectively, be at least partly concentric in order to provide a compact arrangement for the crimp height adjustment mechanism. The invention having been disclosed, a number of variations will now become apparent to those skilled in the art.

Claims: A crimp height adjustment mechanism (4) in a crimping machine having a frame (58), an anvil (42) and a ram (44) carrying a crimping die (46), the ram (42) being secured against rotation and guided for reciprocal movement along a ram axis (R-R) for moving the crimping die (46) toward and away from the anvil (42) between remote and proximate positions with respect to the anvil (42), a bellcrank (66) pivotally attached to said adjustment mechanism (4) at a fulcrum (74), said bellcrank (66) having one end coupled to a drive member (52) for pivoting said bellcrank (66) and the other end pivotally attached to a toggle link (68) interconnected to said ram (44), so that when said bellcrank (66) is pivoted about said fulcrum (74) said ram (44) undergoes said reciprocal movement, the crimping die (46) being adapted to cooperate with the anvil (42) for crimping a terminal when the crimping die (46) is in the proximate position, the adjustment mechanism comprising: a first member (10) fixed with respect to the anvil (42) and having a first threaded portion (12) extending along an adjustment axis (A-A) parallel to the ram axis (R-R), the first threaded portion (12) having a first thread pitch; a second member (20) fixed with respect to said fulcrum (74) and having a second threaded portion (22), which is coaxial to the first threaded portion (12), the second threaded portion (22) having a second thread pitch which differs from the first thread pitch, the second member (20) being secured against rotation; a third member (30) having both a third threaded portion (32), which is adjustably threadedly engaged with the first threaded portion (12), and a fourth threaded portion (34) which is adjustably threadedly engaged with the second threaded portion (22), the third member (30) being rotatable about the adjustment axis (A-A) so as to change an extent of engagement with the first and second threaded portions (12, 22), the third member (30) having actuation means enabling adjustable movement thereof; wherein, upon rotation of the third member (30) the second member (20) and said fulcrum are caused to move along the adjustment axis (A-A) thereby producing a corresponding linear movement of the ram (44) along the ram axis (R-R); wherein actuating rotation of the third member (30) about the adjustment axis (A-A) produces said linear movement of the second member (20) and said fulcrum which is equal to a number of rotations of the third member (30) multiplied by a difference between the first and second pitches. The adjustment mechanism according to claim 1, characterized in that the actuation means includes a manually gripable adjustment wheel (48) fixed to the third member (30). The adjustment mechanism according to claim 1, characterized in that the actuation means includes automatic means for performing the rotation in response to a signal from a sensor. The adjustment mechanism according to any of claims 1 to 3, characterized in that the adjustment axis (A-A) is coincident with the ram axis (R-R). The adjustment mechanism according to any of claims 1 to 4, characterized in that the third member (30) includes an elongated shaft having a coaxial bore, the third threaded portion is defined by an external periphery of the shaft, and the fourth threaded portion is defined by a wall of the bore. The adjustment mechanism according to claim 5, characterized in that the first, second, third and fourth threaded portions (12, 22, 32, 34) are at least partly concentric.

Inventors: WASILKO JOHN MICHAEL, WILSON RICHARD ORLEY, WASILKO, JOHN MICHAEL, WILSON, RICHARD ORLEY
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1994
Main classification: H01R43
IPC codes: H01R43